Interações intra- e intermoleculares dos begomovírus e seus efeitos na adaptação viral e na maquinaria celular do hospedeiro

• Ano de defesa: 2011
• Autor(a) principal: Silva, Fábio Nascimento da
• Orientador(a): Zerbini Júnior, Francisco Murilo
• Banca de defesa: Carvalho, Claudine Márcia , Barros, Everaldo Gonçalves de , Ferreira, Paulo Cavalcanti Gomes
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Begomovírus; Adaptação viral; Hospedeiro
• Palavras-chave em Inglês: Begomoviruses; Viral adaptation; Host
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1062

Begomoviruses (family Geminiviridae) have one or two genomic components, infect dicotyledonous plants and are naturally transmitted by the whitefly Bemisia tabaci (Homoptera: Aleyrodidae). Begomoviruses cause diseases of major economic importance in many crops, especially in tropical and subtropical regions. In Brazil, a viral complex composed of at least eight species, including Tomato rugose mosaic virus (ToRMV), Tomato severe rugose virus (ToSRV) and Tomato yellow spot virus (ToYSV), is responsible for losses in tomato. The complete DNA-B sequences of ToRMV and ToSRV show an identity of 98.2% and the high identity of their common region sequences (96.2%) indicates that the two viruses may share the same DNA-B. For the successful establishment of a viral infection, several interactions are required between begomovirus and host proteins. In this work, experiments were conducted with the following objectives: (1) to analyze the importance of recombination and pseudorecombination in the generation of variability and adaptation to the host of ToRMV and ToSRV; (2) to examine the involvement of two components of the anaphase-promoting complex (APC7 and APC10) in begomovirus replication; (3) to detect and characterize host proteins which interact with the ToYSV movement protein, MP. For the first objective, Nicotiana benthamiana plants were inoculated with all possible combinations of ToRMV and ToSRV DNA-A and DNA-B. Additionally, recombination and nucleotide/amino acid sequence comparisons between ToRMV and ToSRV were performed. The results indicate that ToRMV has both a recombinant and pseudorecombinant origin, and that ToRMV exerts a negative interference over ToSRV. For the second objective, Arabidopsis thaliana plants overexpressing APC7, APC10 and different APC7 mutants were inoculated with Cabbage leaf curl virus (CaLCuV), and viral DNA accumulation was estimated in plants at 14 and 28 days post-inoculation (dpi). The results indicate that APC7 and APC10 negatively affect CaLCuV DNA accumulation, and that both the N-terminal and C-terminal portions of the APC7 protein are involved in this effect. For the third objective, leaves of N. benthamiana were agroinfiltrated with the "bait" construct NTAPi-MP, and 48 hours after agroinfiltration the leaves were collected for extraction and purification of protein heterocomplexes. However, this transient expression assay in leaves of N. benthamiana failed to detect interactions between ToYSV MP and host proteins.